The recent development in the field of information-processing is remarkable and in this connection, recording methods and apparatuses suitable for various systems have been developed and put to use.
Among these, thermal recording process using a heat-sensitive material is widely used in view of various advantages such as lightness, compact, noiseless and excellent and easy operation and maintenance of the the apparatus used therefor.
Among recording sheet used in the thermal recording, an ordinary heat-sensitive recording sheet has, being a color forming type containing color forming agent and developer, such disadvantages that it is expensive, that alteration of records may easily be made, that the recording sheet is liable to be color-stained by heat or with organic solvent and that the recorded images are likely to be discolored in relatively a short period of time.
Under these circumstances thermal-transfer recording system has been attracting public attention as a system for improving aforesaid disadvantages.
In the thermal-transfer recording process, a thermally-transferrable recording medium comprising, on a supporting sheet, a heat-fusible ink layer wherein coloring agents are dispersed in a heat-fusible substance is used and when the medium is heated from the side of the support by a thermal head under the condition that aforesaid ink layer is superposed on a recording sheet onto which an image is to be transferred (usually, paper), the ink layer is melted and transferred onto the recording sheet to form an ink image corresponding to the area to which heat has been applied. Owing to this process, it is possible to record on an ordinary paper and disadvantages of using aforesaid heat-sensitive recording materials have been eliminated.
However, the thermal transfer recording process having such excellent features still has a room for improvement. For example, a recorded image, which is errorneously recorded, cannot be erased easily.
Heretofore, as a method for correcting the erroneous recording in the thermal-transfer recording process, a method (hereinafter referred to as a cover-wrap meathod) wherein a cover coating whose color is identical to that of recording sheet is transferred onto the erroneously recorded portion thereby the erroneously recorded portion is covered and another method (hereinafter referred to as a lift-off method) wherein the erroneously recorded portion is peeled off by an adhesive tape, have been known.
Among aforesaid two methods, the lift-off method that does not deteriorate the reproducibility is considered advantageous when the reprinted image is to be further copied through a transmission mode.
When a wax is used as the pricipal ingredient of a binder for the ink layer, the ink tends to blots on a recording sheet upon printing and it sometimes makes difficult to correct misprints by the lift-off method. On the other hand, when the principal ingredient of the binder in the ink layer is polymer, it is possible, to a certain extent, to correct such misprints by the lift-off method because ink does not easily blots on the recording paper.
It has been difficult to attain both good transferability and fixing characteristics in printing and easy exfoliation from paper in correction at the same time.
In this connection, as disclosed in Japanese Patent Publication Open to Public Inspection No. 230893 (hereinafter referred to as Japanese Patent O.P.I. Publication), an attempt to provide on the ink layer a release layer which accelerates the exfoliation from paper has been made for the purpose of improving correction properties. By this method, although correcting properties be improved, however, the transferability and the fixing property of recorded ink image may be deteriorated and aforesaid problems are not satisfactorily solved.